Eight languages (Arabic, English, French, German, Italian, Mandarin Chinese, Portuguese, Spanish) with 6 differently sized vowel inventories were analysed in terms of vowel formants. A tendency to phonetic reduction for vowels of short duration clearly emerges for all languages. The data did not provide evidence for an effect of inventory size on the global acoustic space and only the acoustic stability of quantal vowel /i/ is greater than other vowels’ in many cases.